Figure 5-27. - A typical automatic residential washer.

direction the drive motor spins. Whenever the drive motor turns in one particular direction, the transmission is shifted to the spin gear. Reversing the motor then automatically shifts the transmission to its agitate gear.

Some washing machine transmissions also have a neutral gear that allows the drive motor to turn without causing either the spin or agitation action to occur. This feature is used during drain operations that call for running the water pump by itself.

MAIN DRIVE MOTOR. - The main drive motor is responsible for converting electrical energy into the kind of mechanical power that is necessary for carrying out the agitation, spin, and pumping actions of the washer. The motor is normally a split-phase induction motor that is rated at about one-half horsepower. Washer motors, almost without exception, operate on 120-volt line power.

A capacitor-start feature is not necessary for washing machines using fractional horsepower drive motors, but a centrifugal switch or relay-start mechanism is always an integral part of the control system of the main drive motor. In some cases, you will find that washer motors are also reversible and they sometimes have built-in speed control windings.

WATER PUMP ASSEMBLY. - The primary purpose of the water pump is to draw used water out of the washer at the end of the washing and rinsing steps and during spin operations. The pump is also used to recirculate the wash and rinse water with the use of a lint filter. The water pump is mechanically driven by the transmission and main drive motor and is operating anytime the main drive motor is running. Consider now the fact that the main drive motor is reversible in most models. It runs in one direction for agitation operations and in the opposite direction for spin operations. This means the water pump runs in both directions as well; and the logical conclusion is the pump moves water in two different directions, depending on which way the main drive motor is turning.

It is possible to take advantage of this two-direction characteristic of the water pump by using it in conjunction with a two-way flapper-valve assembly. The idea is to recirculate the wash or rinse water during agitation operations and to pump the water out of the system during spin operations. By turning the drive motor and pump in the agitation direction (fig. 5-28, view A), valve A is opened and valve B is closed. The water is thus routed through the water recirculation system inside the machine. By turning the drive motor and pump in the spin direction (fig. 5-28, view B), valve A is closed and valve B is opened. Since valve B leads to the wastewater system, moving the water in that direction effectively drains it all out of the washer. This makes it possible to use a flapper-valve assembly for routing the water without using extra electrical controls and timer switches. Some washers control the routing of the pump water by means of solenoid valves.

Figure 5-28. - Operation of a flapper-valve water control system: A. Pump turning in the agitate direction to recirculate the water; B. Pump turning in the spin direction to pump water out of the washer.